Start adding a prelude

move dataclasses import to it

README.md

@@ -61,3 +61,4 @@ PRs are welcome.
 - only compiles one module at a time
 - eliminate all todos in source code
 - panic should probably raise a custom/stdlib exception
+- generate **main** if a module has a main function

gleam.toml

@@ -17,6 +17,7 @@ gleam_stdlib = ">= 0.34.0 and < 2.0.0"
 glance = ">= 0.11.0 and < 1.0.0"
 argv = ">= 1.0.2 and < 2.0.0"
 simplifile = ">= 2.0.1 and < 3.0.0"
+filepath = ">= 1.0.0 and < 2.0.0"
 
 [dev-dependencies]
 gleescript = ">= 1.4.0 and < 2.0.0"

manifest.toml

@@ -19,6 +19,7 @@ packages = [
 
 [requirements]
 argv = { version = ">= 1.0.2 and < 2.0.0" }
+filepath = { version = ">= 1.0.0 and < 2.0.0" }
 glance = { version = ">= 0.11.0 and < 1.0.0" }
 gleam_stdlib = { version = ">= 0.34.0 and < 2.0.0" }
 gleescript = { version = ">= 1.4.0 and < 2.0.0" }

src/generator.gleam

@@ -5,6 +5,7 @@ import gleam/option
 import gleam/string_builder.{type StringBuilder}
 import pprint
 import python
+import python_prelude
 
 pub type Foo
 
@@ -172,7 +173,7 @@ fn generate_type_fields(field: python.Field(python.Type)) -> StringBuilder {
 
 fn generate_type_variant(variant: python.Variant) -> StringBuilder {
   string_builder.new()
-  |> string_builder.append("@dataclass(frozen=True)\n")
+  |> string_builder.append("@dataclasses.dataclass(frozen=True)\n")
   |> string_builder.append("class ")
   |> string_builder.append(variant.name)
   |> string_builder.append(":\n")
@@ -233,6 +234,7 @@ fn generate_plural(
 
 pub fn generate(module: python.Module) -> Result(String, String) {
   string_builder.new()
+  |> string_builder.append(python_prelude.prelude)
   |> string_builder.append_builder(generate_imports(module.imports))
   |> string_builder.append_builder(generate_plural(
     module.custom_types,

src/macabre.gleam

@@ -1,10 +1,12 @@
 import argv
+import filepath
 import generator
 import glance
 import gleam/io
 import gleam/result
 import gleam/string
 import pprint
+import python_prelude
 import simplifile
 import transformer
 
@@ -27,7 +29,11 @@ pub fn write_output(contents: String, filename: String) -> Result(Nil, String) {
 }
 
 pub fn replace_extension(filename: String) -> String {
-  filename |> string.drop_right(5) <> "py"
+  filename |> filepath.strip_extension <> ".py"
+}
+
+pub fn replace_file(path: String, filename: String) -> String {
+  path |> filepath.directory_name |> filepath.join(filename)
 }
 
 pub fn output_result(filename: String, result: Result(Nil, String)) -> Nil {
@@ -44,6 +50,12 @@ pub fn output_result(filename: String, result: Result(Nil, String)) -> Nil {
   }
 }
 
+pub fn output_prelude_file(filepath: String) -> Result(Nil, String) {
+  filepath
+  |> simplifile.write(python_prelude.gleam_builtins)
+  |> result.replace_error("Unable to write prelude")
+}
+
 pub fn compile(module_contents: String) -> Result(String, String) {
   module_contents
   |> parse
@@ -57,6 +69,13 @@ pub fn compile_module(filename: String) -> Result(Nil, String) {
   |> result.try(compile)
   |> pprint.debug
   |> result.try(write_output(_, replace_extension(filename)))
+  |> result.try(fn(_) {
+    // TODO: eventually, this has to be output to a base directory,
+    // not one copy per module.
+    filename
+    |> replace_file("gleam_builtins.py")
+    |> output_prelude_file
+  })
 }
 
 pub fn main() {

src/python.gleam

@@ -1,5 +1,9 @@
 import gleam/option
 
+pub type Context(a) {
+  Context(imports: List(Import), item: a)
+}
+
 pub type Import {
   UnqualifiedImport(module: String, name: String, alias: option.Option(String))
 }

src/python_prelude.gleam

@@ -0,0 +1,5 @@
+pub const gleam_builtins = "
+import dataclasses
+"
+
+pub const prelude = "from gleam_builtins import *\n\n"

src/transformer.gleam

@@ -251,17 +251,8 @@ fn transform_custom_type_in_module(
   module: python.Module,
   custom_type: glance.Definition(glance.CustomType),
 ) -> python.Module {
-  let has_dataclass_import =
-    list.find(module.imports, fn(imp) { imp == python.dataclass_import })
-
-  let imports = case has_dataclass_import {
-    Ok(_) -> module.imports
-    Error(_) -> [python.dataclass_import, ..module.imports]
-  }
-
   python.Module(
     ..module,
-    imports: imports,
     custom_types: [
       transform_custom_type(custom_type.definition),
       ..module.custom_types

test/assignment_test.gleam

@@ -9,7 +9,9 @@ pub fn simple_assignment_test() {
   |> macabre.compile
   |> should.be_ok
   |> should.equal(
-    "def main():
+    "from gleam_builtins import *
+
+def main():
     a = \"hello world\"",
   )
 }
@@ -23,7 +25,9 @@ pub fn mulitple_simple_assignment_test() {
   |> macabre.compile
   |> should.be_ok
   |> should.equal(
-    "def main():
+    "from gleam_builtins import *
+
+def main():
     a = \"hello world\"
     b = 42",
   )

test/custom_types_test.gleam

@@ -8,11 +8,10 @@ pub fn single_variant_custom_type_test() {
   |> macabre.compile
   |> should.be_ok
   |> should.equal(
-    "from dataclasses import dataclass
-
+    "from gleam_builtins import *
 
 class Foo:
-    @dataclass(frozen=True)
+    @dataclasses.dataclass(frozen=True)
     class Bar:
         a: int
 
@@ -31,15 +30,14 @@ pub fn multi_variant_custom_type_test() {
   |> macabre.compile
   |> should.be_ok
   |> should.equal(
-    "from dataclasses import dataclass
-
+    "from gleam_builtins import *
 
 class Foo:
-    @dataclass(frozen=True)
+    @dataclasses.dataclass(frozen=True)
     class Bar:
         a: int
     
-    @dataclass(frozen=True)
+    @dataclasses.dataclass(frozen=True)
     class Baz:
         a: str